Fix unhandled rejection "EncodingError: The source image cannot be de…

…coded"

https://html.spec.whatwg.org/multipage/embedded-content.html#dom-img-decode-dev

src/js/slide/content.js

@@ -417,7 +417,7 @@ class Content {
         // purposefully using finally instead of then,
         // as if srcset sizes changes dynamically - it may cause decode error
         /** @type {HTMLImageElement} */
-        (this.element).decode().finally(() => {
+        (this.element).decode().catch(() => {}).finally(() => {
           this.isDecoding = false;
           this.appendImage();
         });

src/js/util/util.js

@@ -154,7 +154,7 @@ export function removeTransitionStyle(el) {
  */
 export function decodeImage(img) {
   if ('decode' in img) {
-    return img.decode();
+    return img.decode().catch(() => {});
   }
 
   if (img.complete) {